The structure of a watermark, referred to as carrier dot pattern, is a repetitive pattern with the simplest and most basic as a two-dimensional (“2-D”) dot array. The complexity of the dot pattern structure determines the security level. Embedding a latent image object into a watermark is implemented by the modulation on the dot pattern with the latent image object. Observing the latent image using a decoder is a process of demodulation. The decoder is also a structured pattern, which corresponds to a particular dot pattern. It is implemented as an optical instrument, such as gratings, lenses, Ronchi Rulings, special films, or even a photocopier.